1. Field of the Invention
The present invention relates to an automatic watering system for batteries. More specifically, the invention relates to a watering system having a gravity syphon to drain excess water from the battery through a reversible pump and a method for automatically operating the watering system.
2. Description of the Related Art
High power and high voltage batteries are useful in commercial and industrial applications. One application requiring a high voltage and high powered battery is electric vehicles. Several types of electric vehicle batteries require periodic replenishment of electrolyte, including lead acid, nickel cadmium and nickel metal hydride. Recharging the battery causes an electrolysis of the water and results in the evolution of gas. Water is added to the battery cells to maintain an equilibrium of the electrolyte and to completely wet the cell surfaces.
A number of battery watering systems are known in the prior art. Typical of the known automatic watering systems for batteries is U.S. Pat. No. 4,522,896, issued Jun. 11, 1985 to Isard. Isard teaches a battery having a series of connected cells. Each cell has an associated watering cap and an interconnecting means receiving electrolyte from a reservoir. The interconnecting means, reservoir and caps form an essentially closed system. The reservoir selectively communicates with a watering pump, watering cap and flame trap. The interconnecting means also includes a gas purging means to selectively open the closed system to the atmosphere. Gas is selectively purged from within the system during the operation of a gas purging cycle.
Isard requires either a combination liquid/gas type pump such as a diaphragm or peristaltic type pump or the use of a separate air pump to force air through the interconnecting means. Isard does not teach an automatic watering system to alert the operator to a low water condition, operate the pumps and valves to water the battery to the appropriate fill level and detect a fault condition.
U.S. Pat. No. 4,399,200, issued Aug. 16, 1983 to Galloway, teaches a method for controlling a pump in a storage battery. Galloway teaches applying of variable electric voltage to the pump motor to control the flow rate into the battery. This invention is primarily intended for halogen hydride type electric storage batteries and does not detect low electrolyte levels within the battery nor automatically watering each cell in a battery.
The present invention overcomes the deficiencies of the prior art by using a low cost reversible pump to provide water to a battery. The watering caps and conduit are purged of excess water through a gravity syphon. A controller senses water usage to detect proper system operation and disables the charging system to prevent battery damage due to a lapse in watering maintenance.